tinymce-spellchecker: code execution

A security flaw was found in the way Google spellchecker of TinyMCE spellchecker plugin sanitized content of $lang and $str arguments from presence of control characters when checking for matches. A remote attacker could provide a specially-crafted string, to be checked by the TinyMCE spellchecker plugin that, when processed, could lead to arbitrary code execution with the privileges of the user running the TinyMCE spellchecker plugin.